naturally occuring (formed by natural, geogologic procese), inorganic (not alive), crystalline structure (atoms are arranged in orderly, repetitive pattern), solid (at temperatures experienced at the earth's surface), definite chemical composition that usually are made up of two or more elements.

two top elements found in universe

hydrogen and helium

three elements found in earth's crust

oxygen, silicone, aluminum

how is periodic table set up

set up by number of energy shells and atomic mass

elements are organized so that those with similar properties line up in columns

what is an atomic number and what does it mean and what is atomic mass

the atomic number is the number of protons in the nucleus of an atom; atomic mass is the sum of the number of protons and neutrons